1. Technical Field
The present invention relates to a photoconductive switching element, a photoconductive switching element array, a display device, and an image forming apparatus.
2. Related Art
Generally, optical recording-type image display devices that display desired images are known. As such an optical recording-type image display device, for example, as disclosed in JP-A-2000-180888, there is an optical recording-type image display device that includes a photoconductive switching element and a liquid crystal layer that is stacked on the photoconductive switching element.
The photoconductive switching element disclosed in JP-A-2000-180888 includes: two electrode layers (a first electrode layer and a second electrode layer) to which AC voltages are applied; an upper electric charge generating layer that is arranged on the first electrode layer side between the first electrode layer and the second electrode layer; a lower electric charge generating layer that is arranged on the second electrode layer side between the first electrode layer and the second electrode layer; and an electric charge transport layer that is arranged between the upper electric charge generating layer and the lower electric charge generating layer. The upper electric charge generating layer and the lower electric charge generating layer have a function of generating electric charge when light is received. The electric charge transport layer has a function of transporting electric charge that is generated in the upper electric charge generating layer and the lower electric charge generating layer.
In the photoconductive switching element employing such a configuration, when an AC voltage is applied between the first electrode layer and the second electrode layer, a first state in which a current flows from the first electrode layer toward the second electrode layer or a second state in which a current flows from the second electrode layer toward the first electrode layer is taken. In the first state, a boundary face of the electric charge transport layer and the lower electric charge generating layer appears to act as an energy barrier for a movement of the electric charge, and thus, there are problems in that a current does not reliably flows, and the photoconductive switching element is not driven unless the applied voltage is increased and applied in correspondence with the energy barrier. Similarly, in the second state, a boundary face of the electric charge transport layer and the upper electric charge generating layer appears to act as an energy barrier for a movement of the electric charge, and thus, there are problems in that a current does not reliably flow, and the photoconductive switching element is not driven unless the applied voltage is increased and applied in correspondence with the energy barrier.